Hello!
Can you please help? I have a black render while rendering velocity visualisation. When I render my smoke it's ok. As you see I tried to use attributecreate.
I am a beginner in Houdini. In example I've found it works, I do not get why in my case I can't see anything in a renderer.
Maybe there is a better way to render such things? I would love to have some more controls over these trails.
Thank you so much for your help!

Can anyone please help? I can try to explain it better ..

Visualizations are meant to be rendered, there might be meta data attached setting them invisible to the renderer. What material are you using the render the curves? You will need one that sets the color based on the point color. If they are meant to be lit, then you will need lights. If not you need a constant shader. If the lines do not have a width or pscale attribute then the default size might be too small to see. Try adding the width attribute and changing the size. Make sure your render flag is on the correct node, and that your objects are visible. I'm just guessing in the dark here. Without a scene file posted, it will be hard for anyone to help troubleshoot.